1. Field of the Invention
The invention relates to a driving control system for a vehicle.
2. Description of Related Art
A prime mover, such as an internal combustion engine and an electric motor, is mounted on a vehicle, such as an automobile, as a driving source. In addition, the vehicle includes a shift mechanism that is shifted through driver's operation into a driving position (for example, a position at which the vehicle travels forward or a position at which the vehicle travels backward) or a non-driving position (for example, a parking position or a neutral position). Then, when the shift mechanism is operated to the driving position, driving force is transmitted from the prime mover to wheels. On the other hand, when the shift mechanism is operated to the non-driving position, transmission of driving force from the prime mover to the wheels is interrupted.
There is suggested, in a vehicle in which driving force is transmitted from a prime mover to wheels, an execution mode of driving force limiting process for reducing driving force that is output from the prime mover is set on the basis of an operating position of a shift mechanism and then the driving force limiting process is executed on the basis of an operation state of the vehicle.
Japanese Patent Application Publication No. 2010-18174 (JP 2010-18174 A) describes a system that executes driving force limiting process when a shift mechanism is operated from a non-driving position to a driving position in a state where an accelerator operation member is operated. In this system, even when the shift mechanism is operated from the non-driving position to the driving position in a state where the power of the prime mover is increased as a result of operation of the accelerator operation member, driving force that is transmitted from the prime mover to wheels is suppressed to a small driving force. Therefore, a feeling of strangeness experienced by a driver as a result of transmission of driving force is suppressed, and a decrease in drivability is suppressed.
Usually, when the operating position of the shift mechanism is detected, the operating position of the shift mechanism is detected on the basis of an output signal of a shift position sensor attached to the shift mechanism. Therefore, if there is an abnormality in a position detecting device that detects the operating position of the shift mechanism, such as an abnormality in the shift position sensor and an abnormality in a device that processes the output signal of the shift position sensor, it is not possible to properly detect the operating position. In the above-described system, if there is an abnormality in the position detecting device, it is not possible to appropriately reduce driving force through the driving force limiting process, so drivability decreases.